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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 8th Nov 2019, 3:43 pm   #21
factory
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Default Re: Availability of TV valves for Nixie Clock.

Indeed completely obsolete, but combined with the recorder it was used for datalogging from other HP instruments in the 1960's, also the displayed time could be added to the print-out log.

David
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Old 8th Nov 2019, 10:35 pm   #22
MotorBikeLes
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Default Re: Availability of TV valves for Nixie Clock.

I know nothing about these things, but maybe these can help.
You probably all know of the 74141 used to drive the ZM1000 nixie in Grundig 6010 and 6011 colour TVs.
Later of course they went to 7 segment LEDs with the appropriate chips to drive them. This came to mind when I was working on my Advance frequency counter. That used 7 segment "nixie" tubes with a DS8880 driver chip. Not sure if that would be any use to you.
Les.
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Old 9th Nov 2019, 12:56 am   #23
joebog1
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Default Re: Availability of TV valves for Nixie Clock.

Why not use ALL neon cold cathode valves?? BUT make the clock BCD display. I did this with LEDS years ago .
Add all the MSB's, then the LSB's while its counting!! Keeps the mind very agile.

Joe

p.s. I have boxes of CV2213,s !!!.
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Old 10th Nov 2019, 12:41 pm   #24
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Default Re: Availability of TV valves for Nixie Clock.

The 74141 is just a bunch of logic gates configured to energise one output depending which specific combination of inputs is presented. And logic gates are just switches, so it's not an insurmountable problem.

For a display that changes once a second, you could just about get away with decoding the decimal digits using relays. To decode BCD, you would need up to five poles per binary digit. If you used twisted Johnson topology instead of BCD for your counters, you would need five flip-flops and relays per decimal digit (well, only three for the tens of minutes) but fewer poles on each (there are a lot of "don't care"s in the truth table).
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Old 10th Nov 2019, 1:19 pm   #25
TonyDuell
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Default Re: Availability of TV valves for Nixie Clock.

I suggested relays back in message #11.
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Old 11th Nov 2019, 12:47 pm   #26
Argus25
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Default Re: Availability of TV valves for Nixie Clock.

Quote:
Originally Posted by julie_m View Post
The 74141 is just a bunch of logic gates configured to energise one output depending which specific combination of inputs is presented. And logic gates are just switches, so it's not an insurmountable problem.
Actually it is not just that at all. For a TTL IC the '141 is quite amazing, the off state voltage is rated at 60V.

There are plenty of other BCD to decimal TTL decoder IC's, but nothing like this one suited to Nixie tubes.

If you look on ebay you will find that the original TI ones are more difficult to get, but it turns out the Russians cloned them, and as a result plenty of equivalents available.

One interesting thing (and I have yet to meet anyone who knows about this particular example) is what happens when a BCD to 7 segment decimal decoder chip is sent illegal values that correspond to A-F, what they do with that. Some types produce blanks which is handy, others produce a giberish display, but......there is one type that does something really interesting and I could tell you how I found this out, but its too long a story, the IC is a 9374.

On passing it values outside the range of 0 to 9, on the 7 segment display it produces the output H. E. L. P.... not kidding, here is the data sheet :

http://pdf.datasheetcatalog.com/data...ild/DM9374.pdf

I was once greeted with this message on a multi-digit seven segment display under some interesting circumstances.

Last edited by Argus25; 11th Nov 2019 at 1:06 pm. Reason: typo
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Old 11th Nov 2019, 11:34 pm   #27
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Default Re: Availability of TV valves for Nixie Clock.

Quote:
Originally Posted by woodchips View Post
Some thinking around and found a circuit where a pentode would act as a two stable state divider, halving the number of heaters at a stroke.

Still need a lot of pentodes, hence the quick search for the unwanted Uxx valves, but none. Can get EF80, EF91 from places, at 8+ each, which seemed a bit much.
Here you go, brand new B7G pentodes at 61 pence each!
Illustrative listing, there are plenty of others.
https://www.ebay.co.uk/itm/5PCS-6J2-...kAAOSwerdanVDs
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